Search

The rail fastener is an indispensable component used to connect the rail and sleepers in the track structure. Real‐time recognition of the fastener defects plays a vital role in ensuring the safe and stable operation of rail transit. In this paper, an intelligent and innovative method is proposed to detect the fastener defects including the invisible defects appearing as bolt loosening and the visible defects such as the worn or completely missing fasteners by using axle‐box vibration acceleration and deep learning network. First, the dynamical relation between the fastener defects and the axle‐box vibration acceleration is investigated by using the first principle and the vehicle–track dynamical model. Then a defects recognition network is built based on the deep convolution neural network for track fasteners by using the frequency spectrum images of the axle‐box vibration. The results show that the proposed method achieves a classification accuracy of 98.27%. Finally, the track section where the fasteners are most likely to be damaged is investigated, and rail corrugation is found to be a key factor that causes fastener fatigue. [ABSTRACT FROM AUTHOR]

For global template matching (GTM), which is commonly used in the positioning of rail fasteners, only the fastener template is used to search the global image in both two dimensions, which will result in errors in two dimensions, and the lower positioning accuracy will be caused. A positioning method for rail fasteners based on double template matching (DTM) is proposed in this paper, in which the double template contains the rail template and the fastener template. First, the rail template is used to scan the original image in horizontal dimension, and the squared Euclidean distance (SED) is used to obtain the rail positioning in the original image. Combining with the prior knowledge of the fastener template image, the image composed of the rail and the fastener can be obtained, which is called the Rail Area Map (RAM) in this paper. Then, after preprocessing the RAM and the fastener template image, the fastener template image is used to scan the RAM in vertical dimension, and the normalized correlation coefficient (NCC) is used to calculate the similarity between the template and the subgraph of the RAM to achieve precise positioning of the fastener. The proposed DTM method adopts a positioning strategy from coarse to fine, and two templates are used to complete different positioning tasks in their own dimension, respectively. Due to the rail can be precise positioned in horizontal dimension, the error of the fastener positioning in the horizontal dimension can be avoided, and thus, the positioning accuracy can be improved. Experiments on the on-site line fastener images prove that the proposed method can effectively achieve the precise positioning of fasteners. [ABSTRACT FROM AUTHOR]

In recent years, attention has been driven to the direct fastening technology by use of power actuated nail‐type fasteners (PAFs) set in concrete. By means of the series of tests shown in this paper and the high‐speed measuring equipment used, a first approach to the possibility of evaluating the setting performance is demonstrated. The difficulty is to judge whether the operation was successful and whether the fastening can bear the required force, since it is not possible to look into the concrete. For example, it remains hidden whether and, if so, how much the nail was deflected and bent by the concrete. Furthermore, it is unknown how the surrounding concrete was affected by occurring strains and heating as a result of friction. Since the setting process is very fast, it is necessary to use high‐speed measurement technology. In the case of the studies conducted, both digital image correlation (DIC) and thermography were used to record material responses. Following the setting process, the nails and the surrounding concrete were separated and examined with computer tomography (CT). The CT provides the information on the inside of the concrete and one can see cracks and other reactions to the setting process. [ABSTRACT FROM AUTHOR]

This concept paper discusses the effects of the installation condition of fasteners on the life‐cycle performance of noise barriers. Noise barriers that are erected along high‐speed railway lines are loaded by aerodynamic pressure and suction waves due to the passing trains. As an integral part of railway infrastructures their level of safety must be maintained throughout their entire lifetime. On basis of this concept and study, a potential monitoring‐based approach for the assessment of the life‐cycle performance of NBs is briefly introduced. That monitoring‐based approach finds its place in a holistic four‐stage assessment framework, in other words a progressive four‐stage model in which the information content increases with each model stage and thus successively increases the accuracy of the determined structural conditions at the time of observation and the prediction for the remaining service life of the structure. The objectives of this paper should bring relevant insights for the whole holistic four‐stage model. Depending on how far the degradation of the considered noise barrier has already progressed, the corresponding stage of the holistic assessment concept is activated, which enable infrastructure managers to plan their future investments regarding maintenance, retrofit or rebuilt of noise barriers more economically. [ABSTRACT FROM AUTHOR]

Recent research showed that the damage in non‐structural components significantly affects the seismic behaviour of structures, indeed it is crucial to evaluate the seismic behaviour of non‐structural components. For this purpose, the University of Naples "Federico II" started a cooperation with the Hilti Corporation, to evaluate the seismic demand on fasteners connecting drywalls to supporting elements. In particular, the seismic displacement demand on Power Actuated Fasteners (PAF) was obtained through quasi‐static in‐plane cyclic tests on full‐scale drywall partitions. Test specimens consisted of 2285 mm long and 2600 mm high partition walls and in total seven tests were carried‐out at the Lab of the Department of Structures for Engineering and Architecture. A specific test set‐up was developed for the experimental tests and the optimal instrumentation layout was studied to allow to capture the significant measurements on PAFs. A FEMA 461 protocol was employed for all the tests. The paper summarizes the experimental program, describing wall configurations, test set‐up, loading protocol and instrumentation layout. A special focus is dedicated to the comments of experimental results. [ABSTRACT FROM AUTHOR]

This paper proposes a novel method based on continuum damage mechanics (CDM) and machine learning (ML) models to evaluate the vibration fatigue behavior of W1‐type railway fastener clips subjected to high‐frequency vibration. Firstly, static and fatigue tests are conducted on 60Si2Mn spring steel to acquire elastic modulus, tensile strength, and P‐S‐N curves. Subsequently, a CDM model is established, and numerical simulations are performed under various working conditions to obtain the fatigue characteristics of the clips. Finally, the ML model is trained using numerical simulation results, thereby establishing a mapping model between the working conditions and fatigue characteristics. The developed ML model demonstrates high accuracy in predicting the vibration fatigue life of the clips. Moreover, the Shapley Additive Explanations (SHAP) algorithm is employed to elucidate the ML model, revealing that the vibration frequency has a greater impact on the fatigue life of the clips compared to the vibration displacement. Highlights: A novel approach is developed for vibration fatigue assessment of fastener clip.The approach effectively combines the continuum damage model and ML (ANN) model.Static and fatigue tests of 60Si2Mn spring steel are conducted.Fatigue characteristic of clips subjected to high‐frequency vibration is studied. [ABSTRACT FROM AUTHOR]

The fire resistance of fasteners needs to be verified for all failure modes applicable at ambient conditions. Generally, in most cases, for unprotected fasteners loaded in tension, steel failure mode is decisive. But for fasteners made of stainless steel and/or larger (bolt) sizes, concrete cone failure may be the decisive failure mode for small anchorage depths. Due to practical difficulties associated with loading an anchor during a fire test, very limited experimental data is available in literature and that to for relatively small embedment depths. The paper presents the results (6 nos) of the fire tests conducted on expansion anchors (made of stainless steel) with sizes M12 (hef = 70 mm) and M20 (hef = 100 mm). Moreover, the paper also compares the reduction in the concrete cone capacity with exposure duration, predicted as per the current design guidelines and the new set of experimental data obtained in this study. [ABSTRACT FROM AUTHOR]

Screwed‐head fastener is the common fabricated hold‐down bolt for steel structures and machine foundations. Although different models are available for evaluating its structural behavior, there are still aspects that need to be investigated. In particular, conflicting approaches for the design can be found among the European design‐oriented documents. Within this context, a comprehensive experimental study on screwed‐head fasteners under tensile loading was recently carried out at Milan Polytechnic. In this paper, some results are presented and commented which include (a) the presence of cracks and (b) the presence of supplementary reinforcement. In the discussion, predictive models are recalled demonstrating the need for a specific design approach, which should consider the geometry and the resistance of the fastening system, including that of the concrete member. Some design recommendations end the paper as useful guidance for the structural designer. [ABSTRACT FROM AUTHOR]

This paper presents the results of twenty‐one fire tests on unprotected steel‐to‐timber connections with dowel‐type fasteners and one or two slotted‐in steel plates. The experimental results of this type of connections available in existing studies have been mostly limited to a fire resistance duration of 60 min. The tests performed in this study target a significant increase of fire resistance to reach 90 and 120 min. Two configurations of connections with one and two slotted‐in steel plates, i.e., two or four shear planes, were tested. The temperatures were measured at different locations in the wood members and along the steel plates. Two load levels for fire tests were determined on the basis of tests performed at ambient temperature. The experimental results show that the specimens proposed for steel‐to‐timber connections with dowel‐type fasteners are suitable for achieving fire resistance of 90 and 120 min. [ABSTRACT FROM AUTHOR]

Under long-term temperature loading, long bridges stretch and deform, causing the beam and rail to move relative to each other. This phenomenon could cause a gradual slide of the rail relative to the fastener composite pad and ultimately results in the slipping out of the fastener pad at the end of the ballastless track bridge changes. The slipping out of the fastener composite pad changes the longitudinal resistance of the fastener and causes shock of the train on the rail structure due to direct contact between the rail and the tie, thus inhibiting the normal use of the line. In this paper, a reciprocating tensile test was carried out on a WJ-8 small resistance fastener to explore the breaking process of the fastener composite pad, identify the interaction mechanism of the fastener composite pad under the rail, and ultimately determine the influence of the pad on the longitudinal resistance of the fastener. The results show that the two factors that affect the longitudinal resistance of the fastener under reciprocating loading are the surface roughness and displacement of the fastener composite pad. While the surface roughness of the fastener composite pad is the main influencing factor in the early stage, the displacement of the composite pad has a greater impact on the later stage. The research results of this paper can provide an important reference for the maintenance and repair of ballastless track fasteners on bridges. [ABSTRACT FROM AUTHOR]

Extended Hollo‐Bolts (EHBs) are blind bolts that have an extended bolt shank ending in an anchor nut. When used with concrete‐filled tubes, the extension and the anchor in the concrete serve to enhance significantly the performance of both connection components: bolts in tension and tube face in bending. The enhancements are a result of confining the concrete, preventing local buckling of the steel tube and allowing the blind bolt to achieve a tensile strength equal to that of standard bolt+nut fasteners. Overall, the use of the EHB results in a moment‐resisting bolted connection to hollow sections which can achieve rigid behaviour under certain configurations. This paper summarizes research work done to date on such connections at the University of Nottingham. This includes experimental, numerical and analytical modelling. The aim of the work is to provide a fundamental understanding of the behaviour of anchored blind bolt connections to concrete‐filled columns, leading to the specification of appropriate design rules that allow the use of such bolted moment‐resisting connections in practice. The work has proposed analytical models for: connection stiffness, column face‐bending strength considering both single and group behaviour of bolt rows, anchored bolts in tension and anchored bolts under combined tension and shear. [ABSTRACT FROM AUTHOR]

Heavy-haul railway has been developed rapidly in many countries in the world due to its great social and economic benefits. One of the key technologies for heavy-haul railway is the reduction of vibration on the track structures and its surrounding due to impact load induced by the train in service. The vibration behaviors of two kinds of low-vibration track (LVT) systems for heavy-haul railway are investigated in this paper. Firstly, two indoor full-scale low-vibration track models (new LVT and traditional LVT), which include rail, fastener, bearing block, rubber boot, track slab, and foundation base, were constructed according to design drawings. Secondly, the vibration responses of the different track components under the impact excitation of a dropping wheelset were measured. Thirdly, the time-domain characteristics of each track component of the two LVTs were compared by the acquired vibration time-history curves. Finally, the frequency-domain distribution was analyzed, and the vibration reduction performance was evaluated by the comprehensive time-frequency analysis results. The results show the new LVT has lower vibration acceleration, shorter duration of vibration period, lower vibration frequency of track components, and most importantly an obvious vibration reduction effect on the ground. The research results are useful to further optimize the design of LVT to reduce the vibration under train impact load. [ABSTRACT FROM AUTHOR]

On fatigue strength of large‐size bolt‐assemblies in steel constructions under consideration of manufacturing and surface condition related impacts – part 2: evaluation of fatigue tests Manufacturing related impact factor significantly affect the fatigue strength of bolt assemblies used in steel constructions. The effects are taken into account very inconsistently in the design bases, depending on the normative reference used. Especially for bolt assemblies with large diameters, as they are commonly applied in large numbers at towers for wind energy plants, only a very limited experimental background for assessment of relevant impact factors has been available in the past. This paper presents and evaluates results from 20 different fatigue test series, most of them conducted in the recent past on three different high‐strength bolt assembly systems with varying manufacturing conditions. The data base covers a diameter range between M12 and M64 and focuses on test series with high mean stress in a representative order of magnitude for practical application of the bolts. Based on the knowledge given in the relevant literature, the test results are evaluated regarding the impact of different manufacturing related effects. Furthermore, the results are compared to the specifications of the relevant international normative guidelines. In addition to the results of fatigue tests, supplementary metallographic examinations of the fracture surface shape and surface‐layer condition behavior are taken into account. On this basis, the paper derives recommendations for future design considerations and gives an outlook on further expedient investigations. [ABSTRACT FROM AUTHOR]

On fatigue strength of large‐size bolt‐assemblies in steel constructions under consideration of manufacturing and surface condition related impacts – part 1: state of knowledge Manufacturing related impact factors significantly affect the fatigue strength of bolt assemblies used in steel constructions. The effects are taken into account very inconsistently in the design bases, depending on the normative reference used. Especially for bolt assemblies with large diameters, as they are commonly applied in large numbers at towers for wind energy plants, only a very limited experimental background for assessment of relevant impact factors has been available in the past. Part 1 of this paper presents the state of knowledge regarding the decisive influencing variables on the fatigue strength of bolts in steel structures. From this state of knowledge, the authors derive the basis for evaluating existing and (242) previously unpublished results from fatigue tests on axially loaded bolt nut connections up to nominal size M64, which are included in Part 2 of this paper. The focus is on the influence of size and surface layers, the influence of thread fabrication as well as the stress condition from the pulling assembly practice. [ABSTRACT FROM AUTHOR]

Durability and robustness of bolted joints for crane runway beams The paper deals with selected topics related to bolted connections in crane runway girders. First, the behaviour of the connection during tightening and under external loading is described. The significance of the preload for the bolted connection is discussed. The mechanisms underlying losses of preload and securing methods to counteract them are introduced. Subsequently, these securing methods are linked to typical crane runway connections. The paper concludes with considerations for the inspection of the connections in the event of installation and operation of the crane system. [ABSTRACT FROM AUTHOR]

This paper describes tests performed with large, post‐installed bonded fasteners installed in concrete of very low compressive strength. Concrete with several strengths were studied, including strength classes under C20/25. The goal was to determine whether such connections could be designed according to EN 1992‐4, as they deviate from the scope of this standard by the fact that the concrete is outside the permissible compressive strength range. Additionally, these tests aimed to cover the knowledge gap regarding bonded fasteners installed with large‐diameter threaded rods, deep embedment depths, and reduced edge distances, since little research has been done in this area. Tests on single fasteners and on a group of four anchors were performed, and the results were compared with the design values calculated according to EN 1992‐4. Conclusions have been drawn, and possible underestimation of the load‐bearing capacity of such anchorages has been quantified. [ABSTRACT FROM AUTHOR]

Copyright of Bautechnik is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper presents results of a research on robustness of sandwich panels subjected to the accidental load – impact blast wave. The accidental design situation is understood as an unexpected explosion of gas cylinders located in the neighbourhood of the building. Full‐size sandwich panels with lightly profiled, thin‐walled, steel facings and thick softcore were used in the experiments. The conducted field tests allowed for FE model validation in Abaqus/CEA environment. During the experiments, the two high‐speed cameras have been used to record the behavior of the sandwich panel. Furthermore, the failure mechanisms of the sandwich panels and fasteners were also revealed. The research outcomes are based on both field experiments and numerical simulations. [ABSTRACT FROM AUTHOR]

Copyright of Beton- Und Stahlbetonbau is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper focuses on bra damage, specifically damage observed in hook and eye fasteners that are generally located at the backstraps of bras. We describe bra design including the method by which hook and eye fasteners are generally constructed. We assess bra damage in two situations where the damage observed was unexpected given the case scenarios. These were: (i) the complainant of an alleged rape attributed damage to her bra hooks to force during a struggle and (ii) the complainant had earlier manipulated her bra hooks in an incident not related to her complaint. Steriomicroscopy and reconstruction experimentation were necessarily used to assess the bra damage. A systematic approach to damage analysis was employed by the forensic practitioners to correctly identify damage as being a result of mechanical manipulation and therefore as falsified. This paper suggests that more examples of falsified damage should be documented. [ABSTRACT FROM AUTHOR]

Copyright of Beton- Und Stahlbetonbau is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the influence of overly stiff rail fasteners, which are used to stabilize rails on a ballastless track structure, on the mechanism of the occurrence of defects in concrete baseplates. During the analysis, there was a series of field tests performed on a real track, the purpose of which was the assessment of the technical condition of the ballastless track, the assessment of concrete baseplate strength and the verification of the correctness of the rail attachment by means of a fastener. In addition, there was a series of supplementary laboratory tests performed which assessed the relationship between the anchor clamping force and the torque at the assembly stage (the first tightening of the anchors) as well as after the adjustment of the fastening rigidity (loosening and tightening the fastening anchors again). On the basis of the obtained results, a three‐dimensional numerical model of a section of the ballastless track structure was prepared with the use of adaptive solid finite elements. The performed numerical analysis reflecting the real work of a fastener in a track structure were used to identify the causes of defects in concrete baseplates in the analyzed ballastless track structure. [ABSTRACT FROM AUTHOR]

Summary: This paper investigates the influence of the hysteretic shear behavior of postinstalled anchors in concrete on the seismic response of nonstructural components (NSCs) using numerical methods. The purpose of the investigation is to evaluate current design requirements for NSC and their anchorage. Current design guidelines and simplified methods, such as floor response spectra (FRS), typically approach the dynamics of the structure‐fastener‐NSC (SFN) system using simplified empirical formulae. These formulations decouple the structure from the NSC and neglect the behavior of the anchor connection, with the assumption of full rigidity. There is a lack of knowledge on the complex interaction between a host structure, the fastening system, and the NSC, herein referred to as structure‐fastener‐nonstructural interaction (SFNI). More specifically, it is important to investigate whether and how the actual hysteresis shear behavior that takes place in the anchorage could alter the seismic response of the SFN system and its components. Herein, the results of extensive nonlinear dynamic analyses (NLDA) with different models for the anchorage force‐displacement relationship are presented and compared with those obtained with FRS procedures and current code provisions. The anchor models include (a) linear‐elastic, (b) bilinear, and (c) a recently developed hysteresis rule. The results of the NLDA showed that the first two approaches are not able to reflect the behavior of an anchor loaded in dynamic shear. Moreover, when using the more refined hysteresis model, it appears that current code provisions might underestimate the component and anchor shear amplification factors for rigid NSC fixed to the host structure through anchors. [ABSTRACT FROM AUTHOR]

Design model for headed studs as shear connectors under additional tensile loading Headed studs are primarily subjected to shear when used as shear connectors in usual steel‐concrete composite structures. Consequently, initial design rules for shear connectors in composite structures did not address tensile forces directly. In case of horizontally lying headed studs embedded in a thin concrete slab such as in composite bridges, the headed studs may be subjected to tensile forces. For horizontally lying studs, current design rules consider a possible failure caused by a tensile load due to pull‐out by specifying geometric boundary conditions. As a consequence, relatively long shear connectors are required, which lead to uneconomical or impractical embedment lengths of the shear connectors. As meanwhile European code rules for fasteners under shear and tension (EN 1992‐4) have been developed, the upcoming Eurocode 4 refers to them for the design of shear connectors under combined tension and shear in composite structures. The fastening technology allows a direct design for tensile loading for different failure mechanisms, considering the influence of the reinforcement and concrete strength. Following this idea, this paper presents a design model for shear connectors in steel‐concrete composite structures under additional tensile loading based on experimental and numerical investigations considering recent developments in fastening technology. [ABSTRACT FROM AUTHOR]

Copyright of Materialwissenschaft und Werkstoffechnik is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Beton- Und Stahlbetonbau is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Influence of sequential tightening of bolts for rammed flange connections Offshore wind turbines in the North Sea and Baltic Sea are often installed with so‐called monopiles, which require a connection to the transition piece. Alternative to grouted connections rammed ring flange connections have been used since some years, which require also a single case approval due to their special type of construction. For example, the flange surfaces have a non‐parallel flange surface to reduce the contact area between the anvil and the flange. Therefore a scheduled inclined gap to inside occurs if the flange of the transition piece is placed on top. Furthermore, the size and shape of the gap is influenced due to manufacturing and assembly tolerances as well as due to the pile driving procedure. This paper presents the results of parameter studies that analysis the influence of the planned gap and geometric imperfections on the pre‐tension force in the bolt. With the help of finite element analysis, the actual assembly sequence was also taken into account, with the bolts being tightened sequentially. Sequence effects were identified and discussed in the paper. Finally, recommendations are given for future projects with rammed ring flange connections in the offshore sector. [ABSTRACT FROM AUTHOR]

A typical aircraft panel is the assembly consisting of a multitude of thin and lightweight compliant parts. In panel assembly process, part-to-part locating scheme has been widely adopted in order to reduce fixtures. By this locating scheme, a part is located onto the pre-fixed part/subassembly by determinant assembly (DA) holes, and temporary fasteners (e.g., spring pin) are used for joining these DA hole-hole pairs. The temporary fasteners can fasten DA hole-hole pairs in the axial and radial directions of DA holes. The fastening in the radial directions is realized by the expansion of temporary fasteners. Although the usage of temporary fasteners helps reduce the positional differences between hole-hole pairs, their clamping forces thereby may lead to elastic deformation of compliant parts/subassemblies. Limited research has been conducted on such elastic deformation produced by temporary fastener and its influence on assembly dimensional quality. This paper proposes a novel rigid-compliant variation analysis method for aircraft panel assembly, incorporating the deformation in part-to-part locating process. Based on the kinematic theory and linear elasticity deformation assumption, the variation propagation through the locating process, as well as the entire assembly process of an aircraft panel, is formulated. Then, the statistical variation analysis is performed with Monte Carlo (MC) simulation. Finally, the proposed method is validated by a case study. The result shows the deformation in the part-to-part locating process significantly impacts the assembly variations, and our method can provide a more accurate and reliable prediction. [ABSTRACT FROM AUTHOR]

Abstract: Digital form‐fitting – Cog connections for complex steel structures. This paper discusses the potentials of form‐fit connections in steel structures to generate ‘digital details' which are easily adapted to different boundary conditions and organize their manufacturing and assembly. In this paper, a grid shell for a 45 m span ETFE cushion dome and a large membrane façade that use digital detailing as a basic principle for all joints of the structure, will be discussed. The projects demonstrate how the inclusion of simple digital production processes in the detail design enable rational planning, manufacturing and assembly of complex structures. Next to the new challenge in understanding geometric relationships, material properties, and manufacturing techniques, computationally expensive analysis using Finite Volume Elements with nonlinear connection and material models is necessary to the engineering of such details. [ABSTRACT FROM AUTHOR]

Abstract: Limitations to the use of partial shear connection in composite beams with single flange steel beams and composite dowels – Part 1: Theoretical background, methodology and development of FE‐models. The plastic bending resistance design of composite beams with partial shear connection in EC4 is subject to several limitations of use. For instance, the shear connectors, usually shear studs, have to provide sufficient ductility (at least 6 mm deformation capacity) and the geometry of the steel beam is restricted to sections with either equal flanges or only slightly differing areas of top and bottom flange. Furthermore, EC 4 defines a minimum degree of partial shear connection. For composite members with single flange steel section and composite dowels, limitations to the use partial shear connection have not yet been researched. Because of remarkable differences regarding steel section geometry and deformation behaviour of the connectors a simple transfer of EC 4 rules is not possible and likely non‐conservative. In the first of two companion papers on that topic, the theoretical background and the methodology to investigate the limitations of use for partial shear connection are provided. Besides plastic design of several beams sections with partial shear connection, the paper presents the development of nonlinear, 3D FE‐models of composite beams with single flange steel beam and composite dowels, which are validated against experimental beam tests from the literature. [ABSTRACT FROM AUTHOR]

This paper investigates the seismic behaviour of moment-resisting timber frames with beam-column joints fastened with expanded tubes and reinforced with densified veneer wood. Laboratory experiments are carried out on single joints to investigate the cyclic behaviour and, more specifically, the impairment of strength, the ductility ratio and the equivalent viscous damping ratio. A phenomenological numerical model is proposed, where the beams and columns are schematized using linear-elastic beam elements, and the joints with non-linear hysteretic spring calibrated on the results of the experimental tests. The model is used to analyse some representative moment-transmitting structures characterised by different number of bays and storeys. After an estimation of the lateral load-carrying capacity using a pushover analysis, the numerical model is used to estimate the behaviour factor. An incremental dynamic analysis is performed using a set of accelerograms spectrum consistent with a chosen design spectrum. The analyses lead to an estimation of the behaviour factor of 3 and 6 for a portal frame and a five-storey, three-bay frame, respectively, which confirms the highly dissipative behaviour of this kind of moment connection. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Wherever joints in metal lightweight construction are only accessible from one side, joining techniques such as screwing or welding are uneconomic or inapplicable, blind fasteners and especially blind rivets as the most common type are the means of choice. Nevertheless, with the use of blind rivets, problems arise for the structural engineer, because of the lack of proper design rules according to the Eurocode 3. With the research affords of the authors this deficiency was eliminated for the field of normal strength steel in the past. However, with the increasing usage of high‐strength steels in such constructions, new problems emerge and the developed design rules are not valid yet. This paper presents results from quasi‐static tests on blind rivet joints with different steel grades of the components to extend the proposed design rules. Different effects were identified, which lead to a reduced shear resistance of the blind rivets. At the same time the results point out the benefits of high‐strength steels on the load‐bearing behaviour. Furthermore, results from fatigue tests on blind rivet joints are presented. These show a notable influence of the steel grade on the fatigue resistance of the joint as well as the potential for the design of such joints. [ABSTRACT FROM AUTHOR]

Steel framed buildings using digitally fabricated light‐gauge steel sections, combined with an offsite panelised fabrication approach, are becoming more widespread and contribute towards reducing cost and erection time without requiring a large workforce to assemble them. Currently, design standards mandate the use of K‐ or X‐bracing in these structures, thus neglecting the beneficial influence of the sheathing on the behaviour of the system, in particular its resistance to lateral loads. This composite behaviour is largely influenced by the performance of the fasteners, which may exhibit tilting, shear failure and fastener pull‐out. This paper takes a first step towards accounting for composite action between light‐gauge steel stud framing and calcium silicate board by focusing on the behaviour of the screws connecting both. Key failure modes are identified, based on direct pull‐out tests and monotonic and cyclic connector shear tests. Significant pinching behaviour was observed under cyclic excitations. [ABSTRACT FROM AUTHOR]

A novel method is proposed for rail fastener detection based on millimetre‐wave (mmWave) radar, mmWave radar fastener counter (MMW‐FC), which can accurately detect and record the fasteners in real‐time as the train traverses its route. Under circumstances where GNSS signals remain unavailable for prolonged durations, precise train localisation can be accomplished by correlating the number of fasteners derived from this method with the corresponding track map. Initially, MMW‐FC utilises fast Fourier transform and adaptive beamforming to focus the energy reflected from fasteners. Subsequently, it applies an adaptive template‐matching algorithm to detect each fastener. Furthermore, by leveraging known fastener spacing and the average time for trains to pass adjacent fasteners, the Kalman filter can execute precise speed tracking, used as a speed reference when adjusting the matching template adaptively. The experimental results indicate that the proposed method can precisely count the fasteners the train encounters in diverse road and speed conditions. The fastener counter maintains the Counting Error less than 0.067%, the speed error stays below 1.8 km/h, and the maximum values of the mean absolute error and root mean square error for speed are 0.7337 and 0.9584 km/h, respectively. [ABSTRACT FROM AUTHOR]

Numerical simulation of preload losses of bolts in ring flange connections The fatigue performance of bolts in ring flange connections of wind turbine support structures is significantly influenced by the preload level of the bolts. Under operational loading there is a possibility that pre‐tension force is lost due to plastification in the flange or in the bolt. This paper uses a practical example to show the magnitude of such losses and the factors that can significantly influence them. Different load levels, preload forces and different imperfections (parallel gaps) are examined. As a result of the investigations, it can be stated that the preload loss only occurs with a low magnitude and that a high preload always has a positive effect, even if this causes the first plastification at a lower load level. [ABSTRACT FROM AUTHOR]

Ring flange connections for tubular towers, like those for wind turbines or chimneys, are subjected to significant fatigue loading. Next to the bolts, the weld connecting the flange to the tower shell also needs to be checked against fatigue failure. The flange causes local bending moments in the shell, which increase the meridional stress, i. e. stress concentrations occur. In this paper, the influence of geometrical imperfections on such stress concentrations is quantified and the influence of flange geometry on resulting stress is investigated. Recommendations are given for flange dimensions and the design procedure. [ABSTRACT FROM AUTHOR]

This study introduces a new structure of the magnetic lead screw (MLS) intended for wave energy conversion (WEC) applications. One of the key challenges in the application of MLS technology for wave energy lies in the manufacturing of its complicated ideal helix. Structural simplification and processing technology are quite essential in promoting the development of the magnet screw. This study proposes a new method for shaping the desired ideal helix in a simple way with parallelly magnetised magnets. This simple structure reduces manufacturing complexity while maintaining good force density. The magnets with parallel magnetisation are also easier and cheaper to manufacture than the magnets with radial magnetisation. A prototype is manufactured and tested in the laboratory. In addition, the electromagnetic performance of the new structure is evaluated as compared with the magnet screw with ideal helix using the three‐dimensional finite element analysis, verifying the advantages of the proposed structure. [ABSTRACT FROM AUTHOR]

Ring flange connections for tubular towers, such as those for wind turbines or chimneys, are subjected to significant fatigue loading. Apart from the bolts, it is also necessary to carry out a fatigue analysis of the weld connecting the flange to the tower shell. Owing to the presence of the flange, local bending moments occur in the shell which increase the nominal (membrane) stresses, i. e. stress concentrations occur. This paper presents an analytical model for calculating these local bending moments such that stress concentrations can be determined. The analytical model was compared with results from 3D finite element models, and good agreement was found. The results from the model presented are thus deemed appropriate for design purposes. [ABSTRACT FROM AUTHOR]

Design and execution of shear loaded blind rivet joints in steel lightweight constructions Blind rivet technology as a robust, fast and reliable joining technology is used wherever common joining technologies like welding and bolted connections cannot be used because of technological and design reasons or inefficiency. The areas of application for blind rivet technology in steel lightweight constructions are roof and wall claddings as well as the construction of high‐rack‐buildings and residential containers, which have emerged in recent years. Due to normative restrictions concerning the execution of joints with blind rivets in steel lightweight construction and the missing of appropriate design rules according to DIN EN 1993‐1‐3, these constructions fall under the supervision of building authorities. Therefore exists the demand from the building authorities for an experimental proof of usability. This paper presents results from systematic investigations of the shear and bearing resistance of blind rivets and joints produced with them. These investigations should serve as a generally valid extension of the previous design and execution rules of DIN EN 1993‐1‐3 in order to allow a safe design for shear loaded blind rivet joints and at the same time to reduce the time and effort for experimental investigations. [ABSTRACT FROM AUTHOR]

Thread forming screws as an alternative to metric bolts Thread‐forming screws are used in the building industry almost exclusively in the field of lightweight steel construction for fastening thin‐walled profiles to steel or aluminium substructures. The nominal diameters usually vary between 4.2 mm and 6.3 mm. Thread forming screws with nominal diameters of more than 10 mm have the potential to be used as an alternative to metric bolts M10 to M14. Compared to the metric bolt, the thread‐forming screw has the great advantage that the connection does not have to be accessible from both sides. This allows connections that were previously usually achieved by welding. A verification based on the Eurocode 3 1‐8 is currently not available for such connections. This paper describes the special characteristics when using thread‐forming screws as an alternative to metric bolts. At the Versuchsanstalt für Stahl, Holz und Steine at the Karlsruhe Institute of Technology KIT numerous tests were performed to present solutions for the technical challenges of such connections. [ABSTRACT FROM AUTHOR]

Background: Internal fixation of fractures using plates and screws is a common method of treatment. Occasionally the internal fixation fails prior to fracture healing. This often requires revision surgery. Determining the force that internal fixation needs to withstand postoperatively would enable this force to be applied intraoperatively as a test to predict successful fixation. The purpose of the present paper was to determine the minimum stripping torque needed to predict successful internal fixation strength. Methods: The pull-out strength and stripping torque relationships of 4.5-mm cortical bone screws in Sawbones polyurethane foam were determined. Screw forces were directly measured using an LCM load cell washer on a model intertrochanteric neck of femur fracture fixed with 135° 4-hole pin and plate loaded to single leg stance conditions. Additionally a 135° 4-hole pin and plate was mounted on foam blocks and loaded until failure of the shaft screws from the foam occurred. Predicted stripping torque/yield load was determined. Results: Pull-out strength and stripping torque of 4.5-mm cortical bone screws in polyurethane foam have a high degree of linear correlation R2 = 0.95. Direct measurement of shaft screw forces at single leg stance conditions were 585−686 N. This correlated with a stripping torque of 0.9 Nm. Load to yield testing at single leg stance conditions corresponded to a stripping torque of 1.8 Nm. Conclusion: Withstanding 0.9−1.8 Nm of torque during insertion of the femoral shaft screws of a 135° 4-hole pin and plate predicts that the construct will successfully withstand single leg stance. [ABSTRACT FROM AUTHOR]

In this paper, we present results of residual stresses around a cold-worked fastener hole in a thin, finite plate. An analytical model, with plane stress conditions, elastic nonlinear–plastic loading and unloading taken into account, is explicitly presented and has been developed from existing analytical models and methodologies. The solution also accounts for elastic deformation of the mandrel, and is applicable to different sizes of hole and mandrel. A parametric study of the strain-hardening exponent, plate size, Bauschinger parameter and expansion ratio was carried out in the context of the present solution. A sample study of a plate subjected to 4% hole-cold expansion was performed to compare this model with other analytical predictions, finite element simulation and X-ray diffraction experimental results. A brief review of related issues is given. This work is intended to present completely the closed-form equations able to generate residual stress profiles with ease around a cold-expanded hole in a thin, finite plate where boundary conditions are at issue. [ABSTRACT FROM AUTHOR]

Fastenings in concrete are widely applicable in construction. A significant benefit of fastening technology lies in the fact that it can adapt to various geometries and construction sequences. As a result, the need to design and realize a fastening in structural elements with unconventional geometric configurations can be encountered. Existing design standards rely on the concrete capacity design (CCD) method for concrete‐related failures, which typically covers detailing situations with rectangular configurations of the fastenings and the concrete members. However, the lack of guidelines for a wider range of applications may lead to over‐conservative dimensioning or design constraints. This study investigates the influence of beveled concrete edges on the load‐bearing behavior of anchors. As part of the research, a series of experiments and numerical simulations were conducted. The results derived from the investigations are used to develop an analytical concept that extends the area of applicability of the CCD method and can be used for reliable dimensioning of fastenings close to non‐rectangular concrete edges and geometrical boundaries. [ABSTRACT FROM AUTHOR]

In this study, a nonlinear analysis method was proposed to evaluate the serviceability review of a rail fastening system on concrete slab track at railway bridge ends. The serviceability review of the end deck is time-consuming in that it is necessary to calculate the force of fasteners; also, the design is complex because of the many girders, fasteners, and loads. In addition, there is also a case in which a special, expensive fastening device is installed because the stiffness of the rail fastening device is assumed to be linear, and excessive design results are produced by the linear analysis method. In this study, a clamping force test of the fastening system was performed to confirm the real stiffness and the force versus displacement relationship. The test results were applied in the conventional linear analysis method and the proposed nonlinear analysis method to a railway bridge model specimen with concrete slab tracks. The results of the nonlinear analysis method considering the nonlinear stiffness of the rail fastening system through the clamping force test confirmed that the uplift force acting on the rail fastener was considerably reduced compared with that in the linear analysis method. [ABSTRACT FROM AUTHOR]

Abstract: Large‐size HV‐bolt sets in ring‐flange connections are crucial structural members of wind turbine support structures, which are subjected to strong static as well as cyclic loads with considerable numbers of load cycles. Additionally to direct experimental investigations on the structural components themselves, analytical and numerical assessment methods of the bolts performance inside ring‐flanges are valuable engineering tools to gain knowledge about the structural behaviour and to support the development of appropriate design solutions. In this paper, probabilistic fatigue assessment, using Monte Carlo Simulation technique, is utilized to compute the failure probability and to investigate the influence of the scattering parameters on the fatigue performance of HV‐bolt sets in ring‐flange connections. Subsequently, an analytical fatigue calculation approach for large‐size bolts, based on the local strain‐life concept, is introduced. Results from two different methods for determination of required base material properties are compared. The calculations are validated on fatigue tests on HV‐bolt sets and results are discussed with regard to the evaluation of local loading conditions, damage assessment parameters and sensitivity to base material input. [ABSTRACT FROM AUTHOR]

Abstract: Investigations on the load bearing behavior of composite dowels positioned close to the free concrete surface. Composite dowels are an economic alternative to headed studs with various advantages. Modern concrete slabs are dimensioned increasingly thinner and often include several additional functions, for example air conditioning or thermal activation of concrete surfaces. For those applications composite dowels can be positioned horizontally in the concrete slab. Existing investigations on composite dowels describe different failure modes of composite structures such as splitting of the concrete, local compression of the concrete, pry‐out of a concrete cone or plasticizing of the steel teeth. At University of Kaiserslautern composite dowels with positions close to the free surface of the concrete slab were investigated experimentally by push‐out‐tests and on the basis of numerical simulations. In addition, the positive influence of a spiral reinforcement between the steel teeth was analyzed. Further primary and secondary failure mechanisms were observed for this specific position of the composite dowels. These investigations and a design approach will be presented within the paper. [ABSTRACT FROM AUTHOR]

Design of bonded joints from the viewpoint of structural steel engineering. Using bonded joints different issues should be considered: the adhesive bonding systems, taking into account of the substrate and the surface conditions, the design considering permanent and transient actions and the fabrication of the bonding. All of these issues have impact on the reliability often being challenged. One reason is the fact that the real mechanical material behaviour is not considered correctly, so that in practice the calculation results are deviating from the real ones yielding to high safety factors. This paper shows calculation approaches relevant for the structural engineer. Furthermore, options are discussed how hyperelastic as well as elastoplastic descriptions of the adhesive's mechanical behaviour, based on the stress-state, can be transformed from the energetic formulation into a more familiar equilibrium oriented formulation. [ABSTRACT FROM AUTHOR]

Procedure qualification for the determination of tightening parameters for preloaded bolted connections. DIN EN 1090-2 and DIN EN 1993-1-8/NA define tightening procedures for preloaded bolted assemblies tightened at the nut side by simple use thereof. However, in a multitude of applications, preloaded bolted connections are used, which for example are tightened on the head side, designed as tapped hole connections and/or are to be used several times. In these cases, a procedure test is necessary to determine the tightening parameters. The present paper describes the principal procedure for carrying out such a procedure test, in particular the target level of preloading, the length of thread engagement for components with internal threads, the single and multiple use of components, and the boundary criteria for determining the tightening parameters. Furthermore, the procedure is explained using practical examples. [ABSTRACT FROM AUTHOR]

Ultimate load analyses on coupled purlins during bending around the weak axis and torsion. When using a coupled multi-span beam with a Z-shaped cross-section, the question often arises as to which static system the load-bearing behavior can be reproduced in a realistic manner. For bending around the strong axis, spring models are available. For bending around the weak axis and torsion, they unfortunately do not exist. This paper examines this problem and shows the bearing behavior by means of experimental investigations for bending around the weak axis and torsion. [ABSTRACT FROM AUTHOR]

Alternative connection methods for pultruded glass fibre reinforced polymers using small fasteners for lightweight steel structures. Pultruded glass fibre reinforced polymers (GFRP) as load-bearing structure are becoming increasingly prevalent in the construction sector. Up to now steel bolts used in steel construction, with a diameter greater than 10 mm, are used to connect prefabricated components of a load bearing structure on the construction site. This paper presents alternative solutions for the use of this conventional connection method. The properties of bearing type shear connection with thread grooving screws, multi range blind rivets, high strength structural rivets, self drilling screws and lockbolts are examined and evaluated with regard to applicability for the connection of pultruded GFRP profiles. [ABSTRACT FROM AUTHOR]